Activation of resin with controllable ligand density via catalytic oxa-Michael addition and application in antibody purification

This article reported a new strategy for resin activation with divinyl sulfone using catalytic oxa-Michael addition in a controllable manner. By screening a variety of organocatalysts, PPh3 and DMAP stand out with high catalytic efficiency in aprotic solutions. X-ray photoelectron spectroscopy (XPS) analysis indicates high reaction efficiency and less side reactions than traditional aqueous reactions, resulting in high activation density. A maximum activation density of 157.5 ± 1.2 μmol/g resin was achieved in 12 h using PPh3 as catalyst, which is 1.5 times higher than the traditional aqueous reactions. Followed by conjugation with a chromatographic ligand, i.e., 4-mercaptoethyl pyridine (MEP), the resin is capable of antibody purification. Using IgG and BSA as model proteins, adsorption isotherms and dynamic binding behavior of the resin samples were investigated. A higher affinity and dynamic binding capacity of IgG was observed on resins with higher ligand density. Finally, the resin samples were applied to the purification of a therapeutic monoclonal antibody from cell culture supernatant. The recovery of the resin samples with high ligand density are 70% higher than those of the commercial resin (MEP HyperCel). Moreover, our method achieves a controllable chromatographic ligand density by varying reaction times, which is useful to clarify the density-affinity relationship and improve process-scale antibody purification.